<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>主页</title>
    <link rel="stylesheet" th:href="@{/layui/css/layui.css}">
    <link rel="stylesheet" th:href="@{lib/css/main.css}">
    <link rel="stylesheet" th:href="@{/lib/css/public.css}">
    <script th:src="@{/lib/js/jquery-3.4.1.min.js}"></script>
    <script th:src="@{/layui/layui.js}"></script>
</head>
<style>
    .body{
        margin-left: 200px;
        float: left;
    }


</style>

<body>
<div th:replace="menu/left :: leftbar"></div>

<div th:replace="menu/top :: topbar"></div>

<div class="body">

    这是内容
</div>
<script>
    //注意：导航 依赖 element 模块，否则无法进行功能性操作
    layui.use('element', function(){
        var element = layui.element;

        //…
    });

</script>
</body>
</html>